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Chemistry LibreTexts

Genie in a Bottle

Rub the bottle to get the genie.

Concept

Energy is released (as heat) when hydrogen peroxide decomposes. The water turns to a gas and is pushed out of the flask.

Materials

  • 500 ml Florence or Erlenmeyer flask
  • 1 rubber stopper
  • 20 ml of 30% hydrogen peroxide, H2O2
  • 1/4 teaspoon of powdered Manganese Dioxide, MnO2
  • Tissue paper
  • 8 in. piece of string
  • Safety goggles
  • Plastic gloves
  • Aluminum foil

Directions

  1. Wrap foil around flask.
  2. Put MnO2 in the center of the single thickness of tissue paper and gather the four corners and twist.
  3. Tie the string around the twisted part.
  4. Add the H2O2 into the flask.
  5. Lower the tissue on the string into the flask, but do not let it touch the H2O2.
  6. Put the rubber stopper on to stop the MnO2 from falling in.
  7. When ready, release the rubber stopper to let the MnO2 fall to the bottom and watch.

Introduction

Over the summer, I went on an exotic voyage to the far east. We discovered many interesting artifacts and I brought this one to show you all today. It's so bizarre. I wonder what's inside(put to ear to listen). I think I hear something or someone.They said to open the bottle. What do you think? Should I open it? (open flask).

geniebottle.GIF

Reaction

Manganese Dioxide acts as a catalyst to decompose the Hydrogen Peroxide which releases oxygen, water, and heat energy. The amount of energy given off in this very exothermic reaction is sufficient to cause the water to boil. The gas molecules of the water move rapidly producing a white cloud of steam. This is a similar reaction found in the elephant toothpaste demo.

2H2O2 (g) + MnO2 (s) --> 2O2(g) + 2H2O (g) + MnO2 (s) + Heat

Safety

  1. Concetrated H2O2 (35%) is much stronger than that found in drug stores. Be careful.
  2. Wear protective gloves when handling the Hydrogen Peroxide which is a very corrosive liquid.
  3. Do not hold flask while doing demo. After MnO2 is added to Hydrogen Peroxide, the flask becomes very hot.

Waste Disposal

  • Dispose of remaining contents into sink.

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